We have been studying the role that protein degradation plays in regulating cell growth control, through the study of a mutant defective in protein degradation, the E. coli lon mutant. This strain is defective in cell division regulation after DNA damage; we have demonstrated that this defect is due to accumulation of a highly unstable cell division inhibitor, the product of the Su1A gene. We have demonstrated that overproduction of SulA is sufficient to stop formation of septa in E. coli, and have genetically identified the probable target of Su1A action. SulA protein has been purified from cells which overproduce SulA, and antibody raised to the purified protein. This will allow future detection of Su1A degradation patterns in vivo and development of in vitro assays for Su1A degradation. 1on mutants also overproduce capsular polysaccharide, and we have developed a system for the simple assay of the regulation of the genes necessary for capsule synthesis (cps) using cps: :lac operon fusions. Using these strains, we have isolated and mapped mutations in three genes which regulate capsule synthesis (cpsR, cpsS, and cpsT). From genetic experiments, we have demonstrated the existence of a cascade of regulatory interactions to regulate transcription from the cps structural genes. Future work will allow us to examine this cascade in vitro, and identify the precise role of lon. Using insertional mutagenesis, we have isolated null mutations in lon, demonstrating for the first time the dispensability of this gene for E. coli growth. Our analysis of the proteolysis defect in these mutants will allow us to identify other proteases in the cell with properties similar to lon.